The aim of this study was to provide a better understanding of the main difficulties hindering undergraduate biology students in learning histology. The study utilized a selfadministered questionnaire which included three closed-ended and two open-ended questions: (1) if students had difficulty in learning about each tissue type;(2) what might be the problem in learning about the tissue at hand; (3) which topics were the most difficult; (4) what were the possible reasons that made image identification of tissue types difficult; and (5) how to improve the course curriculum from a student perspective. The survey was administered to 139 undergraduate biology students enrolled in a histology course, of which 101 surveys were completed and analyzed both qualitatively and quantitatively. The topics that students experienced the most difficulties with were: nervous tissue, plant tissues, bone tissues, and glandular epithelial tissue. The main reasons students experienced difficulties with these tissue types, according to the students themselves, were the nature of the topic, grasping the terminology used, and insufficient teaching time. Students suggested the adoption of strategies such as: teaching based on practical tasks; reducing the content of the histology curriculum; adding anatomy subjects; and making histology education more interesting. Anat Sci Educ 12:541-549.

Background/Aims: Interleukin-6 (IL-6) is a major cytokine controlling body weight and metabolism, at least in part through actions in the central nervous system (CNS) from local sources. Methods: We herewith report results obtained in conditional IL-6 KO mice for brain cells (Il6ΔGfap and Il6ΔSyn). Results: The reporter RiboTag mouse line demonstrated specific astrocytic expression of GFAP-dependent Cre in the hypothalamus but not in other brain areas, whereas that of synapsin 1-dependent Cre was specific for neurons. Feeding a high-fat diet (HFD) or a control diet showed that Il6ΔGfap and Il6ΔSyn mice were more prone and resistant, respectively, to HFD-induced obesity. Energy intake was not altered in HFD experiments, but it was reduced in Il6ΔSyn male mice following a 24-h fast. HFD increased circulating insulin, leptin, and cholesterol levels, decreased triglycerides, and caused impaired responses to the insulin and glucose tolerance tests. In Il6ΔGfap mice, the only significant difference observed was an increase in insulin levels of females, whereas in Il6ΔSyn mice the effects of HFD were decreased. Hypothalamic Agrp expression was significantly decreased by HFD, further decreased in Il6ΔGfap, and increased in Il6ΔSyn female mice. Hypothalamic Il-6 mRNA levels were not decreased in Il6ΔSyn mice and even increased in Il6ΔGfapmale mice. Microarray analysis of hypothalamic RNA showed that female Il6ΔGfap mice had increased interferon-related pathways and affected processes in behavior, modulation of chemical synaptic transmission, learning, and memory. Conclusion: The present results demonstrate that brain production of IL-6 regulates body weight in the context of caloric excess and that the cellular source is critical.

This study aimed at examining the histological structure of the pecten oculi in the adult yellow‐legged gull, Larus michahellis, and at two moments of postnatal development: during the posthatch (nestling) and juvenile periods. Particular attention was paid to differences in the diameter of vessels, the thickness of the basement membrane, and ultrastructural features of endothelial and pigmented stromal cells. Capillary endothelial cells displayed numerous microvillous‐like folds projecting from their internal and external surfaces. Intercellular spaces between capillaries were occupied by pigmented stromal cells. The ultrastructure of pecten oculi underwent noticeable changes during postnatal development. The examination of the capillaries in nestlings, juveniles, and adults revealed that the formation process of vessels and pigmented stromal cells did not complete itself in the posthaching phase. The prominent feature of endothelial cells of capillaries in nestlings was that the microvilli were longer than in juvenile and adult cells, and the capillary lumen was therefore reduced. In this sense, their pigmented stromal cells showed fewer melanosomes, lacked intercellular spaces, and cellular junctions could still be observed. These results provide evidence that the pecten oculi during the posthatching phase maintains immature morphological features consistent with a role of pigmented stromal cells in the blood‐retina barrier.

The health effects of mercury vapor exposure on the brain in volcanic areas have not been previously addressed in the literature. However, 10% of the worldwide population inhabits in the vicinity of an active volcano, which are natural sources of elemental mercury emission. To evaluate the presence of mercury compounds in the brain after chronic exposure to volcanogenic mercury vapor, a histochemical study, using autometallographic silver, was carried out to compare the brain of mice chronically exposed to an active volcanic environment (Furnas village, Azores, Portugal) with those not exposed (Rabo de Peixe village, Azores, Portugal). Results demonstrated several mercury deposits in blood vessels, white matter and some cells of the hippocampus in the brain of chronically exposed mice. Our results highlight that chronic exposure to an active volcanic environment results in brain mercury accumulation, raising an alert regarding potential human health risks. These findings support the hypothesis that mercury exposure can be a risk factor in causing neurodegenerative diseases in the inhabitants of volcanically active areas.

Mercury accumulation has been proposed as a toxic factor that causes neurodegenerative diseases. However, the hazardous health effects of gaseous elemental mercury exposure on the spinal cord in volcanic areas have not been reported previously in the literature. To evaluate the presence of volcanogenic inorganic mercury in the spinal cord, a study was carried out in São Miguel island (Azores, Portugal) by comparing the spinal cord of mice exposed chronically to an active volcanic environment (Furnas village) with individuals not exposed (Rabo de Peixe village), through the autometallographic silver enhancement histochemical method. Moreover, a morphometric and quantification analysis of the axons was carried out. Results exhibited mercury deposits at the lumbar level of the spinal cord in the specimens captured at the site with volcanic activity (Furnas village). A decrease in axon calibre and axonal atrophy was also observed in these specimens. Given that these are relevant hallmarks in the neurodegenerative pathologies, our results highlight the importance of the surveillance of the health of populations chronically exposed to active volcanic environments.

Opinión del Alumnado sobre el Uso de WhatsApp en el Aprendizaje de la Histología Durante COVID-19 Students' Views About Using WhatsApp for Learning Histology During COVID-19 García M.; Navarro-Sempere, A. & Segovia Y.

The morphology of the retina of the adult Yellow-legged Gull, Larus michahellis, was examined in transverse sections under light microscopy in order to study the retinal adaptations to their specific photic environment that determines their behaviour. We identified rods, single cones and unequal double cones. Although it is a duplex retina, cones are preponderant and coloured oil droplets are present in their inner segments. As several colours in oil droplets are observed, it seems reasonable to conclude that several types of cones are present. Moreover, more cones per unit area are found in the central regions of the retina than in peripheral regions. A probable area centralis is observed. In the inner nuclear layer, two types of horizontal cells, and bipolar and amacrine cells can be recognised. Also, ganglion cells, characterised by prominent nuclei and nucleoli, vary in size and abundance among different regions in the retina. Comparisons are made with the retinae of other marine birds. The morphological characteristics of this retina indicate that Larus michahellis possesses: a good ability to discriminate colour; complex visual processing in the inner retina in order to mediate contrast and motion perception; and an elevated acuity in areas of high ganglion cell density.

NAVARRO-SEMPERE, A.; SEGOVIA, Y. & GARCÍA, M.Comparative analysis of retinal ganglion cell topography and behavioral ecology in australian marsupials. Int. J. Morphol., 36(1):248-257, 2018. SUMMARY:The retina of vertebrates shows adaptations to the visual environment in which they evolve. Thus, there exists a relationship between the topographic distribution of retinal cells, the adaptive strategies employed, and habitat, so that, analyses of retinal ganglion cell topography provide information about the behavioral ecology of a species. Although these relationships are well documented in many vertebrates, including mammals, for species within the marsupial order, they are not well understood. However, marsupials represent an ideal group for comparative analyses of interspecific variations in the mammalian visual system because they contain species that vary in both lifestyle and habitat preference. In this paper the interspecific variation in retinal ganglion cell topography in 13 species of Australian marsupials is reviewed. The species that live in open habitats have well-defined elongated visual streaks. In contrast, forest-dwelling marsupials have poorly defined visual streaks and a more radially symmetrical arrangement of retinal ganglion cell (RGC) isodensity contours. However, the organization and degree of elongation of the visual streak varies considerably among species. The results indicate that the apparent interspecific variation is associated with activity pattern and habitat as opposed to the phylogenetic relationships among species.